Storm in a storm glass

Meet my Fitzroy storm glass. I got it from Australian Geographic and it's got a magic mix of secret chemicals that enable it to predict the weather. Or so they say.
 
Storm glasses were popular with English sea captains, like Fitzroy, captain of the Beagle, with Darwin aboard, on his trip around the world. They got back OK, so there must be something to it, you'd think.



















The appearance of the fluid tells you all you need to know. It can be clear, cloudy, full of bubbles, dots, stars, or flakes. Just check against the key, and sail on confidently.




I've watched it carefully for a few days now, and you sure do get all those effects. But I haven't actually seen a correlation with the weather.


The smart money is on temperature though. That's about all that seems to drive it. If it's hot it's clear. If it's cool it's cloudy. The other stuff comes in between.








It makes an excellent curiosity and talking point though!